In a simple construction, a conventional color negative film intended for in-camera exposure typically takes the following form:
______________________________________ CNF-I ______________________________________ OC BRLU YFL GRLU IL RRLU AHL TRANSPARENT FILM SUPPORT ______________________________________
On the transparent film support are coated in the order shown, a series of processing solution penetrable hydrophilic colloid layers: antihalation layer AHL, a red recording layer unit RRLU containing a red sensitized silver iodobromide (AgIBr) emulsion and a cyan dye-forming coupler, an interlayer IL containing an oxidized developing agent scavenger, a green recording layer unit GRLU containing a green sensitized AgIBr emulsion and a magenta dye-forming coupler, a yellow filter layer YFL containing a Carey Lea silver or a processing solution decolorizable yellow filter dye and an oxidized developing agent scavenger, a blue recording layer unit BRLU containing blue sensitive (optionally blue sensitized) AgIBr emulsion and a yellow dye-forming coupler, and a transparent protective overcoat OC. In the simplest possible construction capable of producing a color negative image, all of the hydrophilic colloid layers, except BRLU, GRLU and RRLU can be omitted. In the overwhelming majority of practical applications all of the layers of CNF-I described above are employed and, most commonly, many additional addenda are incorporated for performance enhancement.
Camera speed films in general and color negative films in particular employ emulsions that contain silver iodobromide grains. Iodide in concentrations down to about 0.1 mole percent, based on silver, are well known to increase speed without increasing granularity. However, iodide ion released from the grains during development has the known disadvantage of slowing development rates. The reduction of development rates shows up particularly in the red recording layer unit of color negative films, since this recording layer unit receives developing agent only after the developer solution has already penetrated the overlying blue and green recording layer units.
The Kodak Flexicolor.TM. C-41 process is commonly employed for processing imagewise exposed color negative films. Since minor adjustments of the C-41 process are undertaken from time to time, the following detailed description is provided:
______________________________________ Develop 3'15" Developer 37.8.degree. C. Bleach 4' Bleach 37.8.degree. C. Wash 3' 35.5.degree. C. Fix 4' Fixer 37.8.degree. C. Wash 3' 35.5.degree. C. Rinse 1' Rinse 37.8.degree. C. Developer Water 800.0 mL Potassium Carbonate, anhydrous 34.30 g Potassium bicarbonate 2.32 g Sodium sulfite, anhydrous 0.38 g Sodium metabisulfite 2.96 g Potassium Iodide 1.20 mg Sodium Bromide 1.31 g Diethylenetriaminepentaacetic acid 8.43 g pentasodium salt (40% soln) Hydroxylamine sulfate 2.41 g N-(4-amino-3-methylphenyl)-N-ethyl- 4.52 g 2-aminoethanol Water to make 1.0 L pH @ 26.7.degree. C. 10.00 +/- 0.05 Bleach Water 500.0 mL 1,3-Propylenediamine tetra- 37.4 g acetic acid 57% Ammonium hydroxide 70.0 mL Acetic acid 80.0 mL 2-Hydroxy-1,3-propylenediamine 0.8 g tetraacetic acid Ammonium Bromide 25.0 g Ferric nitrate nonahydrate 44.85 g Water to make 1.0 L pH 4.75 Fix Water 500.0 mL Ammonium Thiosulfate (58% solution) 214.0 g (Ethylenedinitrilo)tetraacetic acid 1.29 g disodium salt, dihydrate Sodium metabisulfite 11.0 g Sodium Hydroxide (50% solution) 4.70 g Water to make 1.0 L pH at 26.7.degree. C. 6.5 +/- 0.15 Rinse Water 900.0 mL 0.5% Aqueous p-tertiary-octyl-(.alpha.- 3.0 mL phenoxypolyethyl)alcohol Water to make 1.0 L ______________________________________
Koboshi et al U.S. Pat. No. 4,937,178 discloses a process of producing a color negative image having a magenta dye density equal to at least 2 during a development time of not more than 3 minutes employing an imagewise exposed color negative film that produces a magenta dye density of less than 2 during development under conditions essentially similar to the Flexicolor.TM. C-41 process described above, except that to get higher magenta dye densities in a shorter development time "unconventionally active conditions" are employed. Development temperatures above 40.degree. C. are indicated to be one approach for reducing development times, but, with various adjustments of the recording layer units, lower development temperatures are shown to be feasible. Koboshi et al requires that the silver halide grains contain at least 0.1 mole percent iodide, based on silver.
The use of dopants in silver halide grains to modify perfonnance characteristics is well recognized in the art. The use as dopants of coordination complexes of a Group 8 metal and one or more ligands more electronegative than halide ligands to increase photographic speed by acting as shallow electron traps (SET's) is disclosed in Research Disclosure, Vol. 367, November 1994, Item 36736. The SET dopants are identified to be useful for increasing photographic speed.